[clang-tidy] Use shrink_to_fit instead of copy and swap trick
The shrink_to_fit() method is more readable and more effective than the copy and swap trick to reduce the capacity of a shrinkable container. Note that, the shrink_to_fit() method is only available in C++11 and up. Example: std::vector<int>(v).swap(v); will be replaced with v.shrink_to_fit(); http://reviews.llvm.org/D7087 Patch by Gábor Horváth! llvm-svn: 226912
This commit is contained in:
Alexander Kornienko
parent
a6354cae56
commit
e94b7c24c8
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@ -8,6 +8,7 @@ add_clang_library(clangTidyReadabilityModule
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NamespaceCommentCheck.cpp
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ReadabilityTidyModule.cpp
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RedundantSmartptrGet.cpp
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ShrinkToFitCheck.cpp
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LINK_LIBS
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clangAST
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@ -15,6 +15,7 @@
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#include "ElseAfterReturnCheck.h"
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#include "FunctionSize.h"
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#include "RedundantSmartptrGet.h"
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#include "ShrinkToFitCheck.h"
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namespace clang {
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namespace tidy {
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@ -33,6 +34,8 @@ public:
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"readability-function-size");
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CheckFactories.registerCheck<RedundantSmartptrGet>(
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"readability-redundant-smartptr-get");
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CheckFactories.registerCheck<ShrinkToFitCheck>(
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"readability-shrink-to-fit");
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}
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};
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@ -0,0 +1,109 @@
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//===--- ShrinkToFitCheck.cpp - clang-tidy---------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "ShrinkToFitCheck.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/ADT/StringSet.h"
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#include "clang/AST/ASTContext.h"
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#include "clang/ASTMatchers/ASTMatchFinder.h"
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#include "clang/Lex/Lexer.h"
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using namespace clang::ast_matchers;
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namespace {
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bool isShrinkableContainer(llvm::StringRef ClassName) {
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static const llvm::StringSet<> Shrinkables = [] {
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llvm::StringSet<> RetVal;
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RetVal.insert("std::deque");
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RetVal.insert("std::basic_string");
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RetVal.insert("std::vector");
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return RetVal;
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}();
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return Shrinkables.find(ClassName) != Shrinkables.end();
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}
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}
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namespace clang {
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namespace ast_matchers {
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AST_MATCHER(NamedDecl, stlShrinkableContainer) {
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return isShrinkableContainer(Node.getQualifiedNameAsString());
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}
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} // namespace ast_matchesr
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} // namespace clang
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namespace clang {
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namespace tidy {
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void ShrinkToFitCheck::registerMatchers(MatchFinder *Finder) {
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// Swap as a function need not to be considered, because rvalue can not
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// be bound to a non-const reference.
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const auto ShrinkableAsMember =
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memberExpr(member(valueDecl().bind("ContainerDecl")));
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const auto ShrinkableAsDecl =
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declRefExpr(hasDeclaration(valueDecl().bind("ContainerDecl")));
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const auto CopyCtorCall = constructExpr(
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hasArgument(0, anyOf(ShrinkableAsMember, ShrinkableAsDecl,
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unaryOperator(has(ShrinkableAsMember)),
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unaryOperator(has(ShrinkableAsDecl)))));
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const auto SwapParam = expr(anyOf(
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memberExpr(member(equalsBoundNode("ContainerDecl"))),
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declRefExpr(hasDeclaration(equalsBoundNode("ContainerDecl"))),
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unaryOperator(has(memberExpr(member(equalsBoundNode("ContainerDecl"))))),
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unaryOperator(
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has(declRefExpr(hasDeclaration(equalsBoundNode("ContainerDecl")))))));
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Finder->addMatcher(
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memberCallExpr(on(hasType(namedDecl(stlShrinkableContainer()))),
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callee(methodDecl(hasName("swap"))),
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has(memberExpr(hasDescendant(CopyCtorCall))),
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hasArgument(0, SwapParam.bind("ContainerToShrink")),
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unless(isInTemplateInstantiation()))
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.bind("CopyAndSwapTrick"),
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this);
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}
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void ShrinkToFitCheck::check(const MatchFinder::MatchResult &Result) {
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const LangOptions &Opts = Result.Context->getLangOpts();
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if (!Opts.CPlusPlus11)
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return;
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const auto *MemberCall =
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Result.Nodes.getNodeAs<CXXMemberCallExpr>("CopyAndSwapTrick");
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const auto *Container = Result.Nodes.getNodeAs<Expr>("ContainerToShrink");
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FixItHint Hint;
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if (!MemberCall->getLocStart().isMacroID()) {
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std::string ReplacementText;
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if (const auto *UnaryOp = llvm::dyn_cast<UnaryOperator>(Container)) {
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ReplacementText =
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Lexer::getSourceText(CharSourceRange::getTokenRange(
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UnaryOp->getSubExpr()->getSourceRange()),
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*Result.SourceManager, Opts);
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ReplacementText += "->shrink_to_fit()";
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} else {
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ReplacementText = Lexer::getSourceText(
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CharSourceRange::getTokenRange(Container->getSourceRange()),
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*Result.SourceManager, Opts);
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ReplacementText += ".shrink_to_fit()";
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}
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Hint = FixItHint::CreateReplacement(MemberCall->getSourceRange(),
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ReplacementText);
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}
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diag(MemberCall->getLocStart(), "the shrink_to_fit method should be used "
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"to reduce the capacity of a shrinkable "
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"container")
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<< Hint;
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}
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} // namespace tidy
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} // namespace clang
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@ -0,0 +1,35 @@
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//===--- ShrinkToFitCheck.h - clang-tidy-------------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_SHRINK_TO_FIT_H
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#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_SHRINK_TO_FIT_H
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#include "../ClangTidy.h"
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namespace clang {
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namespace tidy {
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/// \brief Replace copy and swap tricks on shrinkable containers with the
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/// \c shrink_to_fit() method call.
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///
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/// The \c shrink_to_fit() method is more readable and more effective than
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/// the copy and swap trick to reduce the capacity of a shrinkable container.
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/// Note that, the \c shrink_to_fit() method is only available in C++11 and up.
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class ShrinkToFitCheck : public ClangTidyCheck {
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public:
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ShrinkToFitCheck(StringRef Name, ClangTidyContext *Context)
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: ClangTidyCheck(Name, Context) {}
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void registerMatchers(ast_matchers::MatchFinder *Finder) override;
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void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
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};
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} // namespace tidy
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} // namespace clang
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#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_SHRINK_TO_FIT_H
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@ -0,0 +1,75 @@
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// RUN: $(dirname %s)/check_clang_tidy.sh %s readability-shrink-to-fit %t
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// REQUIRES: shell
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namespace std {
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template <typename T> struct vector { void swap(vector &other); };
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}
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void f() {
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std::vector<int> v;
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std::vector<int>(v).swap(v);
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// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: the shrink_to_fit method should be used to reduce the capacity of a shrinkable container [readability-shrink-to-fit]
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// CHECK-FIXES: {{^ }}v.shrink_to_fit();{{$}}
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std::vector<int> &vref = v;
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std::vector<int>(vref).swap(vref);
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// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: the shrink_to_fit method should
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// CHECK-FIXES: {{^ }}vref.shrink_to_fit();{{$}}
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std::vector<int> *vptr = &v;
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std::vector<int>(*vptr).swap(*vptr);
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// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: the shrink_to_fit method should
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// CHECK-FIXES: {{^ }}vptr->shrink_to_fit();{{$}}
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}
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struct X {
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std::vector<int> v;
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void f() {
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std::vector<int>(v).swap(v);
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// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: the shrink_to_fit method should
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// CHECK-FIXES: {{^ }}v.shrink_to_fit();{{$}}
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std::vector<int> *vptr = &v;
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std::vector<int>(*vptr).swap(*vptr);
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// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: the shrink_to_fit method should
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// CHECK-FIXES: {{^ }}vptr->shrink_to_fit();{{$}}
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}
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};
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template <typename T> void g() {
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std::vector<int> v;
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std::vector<int>(v).swap(v);
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// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: the shrink_to_fit method should
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// CHECK-FIXES: {{^ }}v.shrink_to_fit();{{$}}
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std::vector<T> v2;
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std::vector<T>(v2).swap(v2);
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// CHECK-FIXES: {{^ }}std::vector<T>(v2).swap(v2);{{$}}
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}
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template <typename T> void g2() {
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std::vector<int> v;
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std::vector<int>(v).swap(v);
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// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: the shrink_to_fit method should
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// CHECK-FIXES: {{^ }}v.shrink_to_fit();{{$}}
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T v3;
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T(v3).swap(v3);
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// CHECK-FIXES: {{^ }}T(v3).swap(v3);{{$}}
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}
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#define COPY_AND_SWAP_INT_VEC(x) std::vector<int>(x).swap(x)
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// CHECK-FIXES: #define COPY_AND_SWAP_INT_VEC(x) std::vector<int>(x).swap(x)
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void h() {
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g<int>();
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g<double>();
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g<bool>();
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g2<std::vector<int>>();
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std::vector<int> v;
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COPY_AND_SWAP_INT_VEC(v);
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// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: the shrink_to_fit method should
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// CHECK-FIXES: {{^ }}COPY_AND_SWAP_INT_VEC(v);{{$}}
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}
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